I. Field of the Invention
The present invention relates to an improved fastener for releasably securing a valve actuator housing to a valve mounting flange.
II. Description of the Prior Art
Many types of valves, for example, pipeline valves, include a valve stem the rotation of which actuates the valve. In most cases, it is impossible to physically rotate the valve stem by hand so that typically a valve actuator is secured on top of the valve. The valve actuator lockingly receives the valve stem and includes gear means for rotatably driving the valve stem.
In order to attach the valve actuator to the valve, it has been the previous practice to provide both an annular mounting flange on top of the valve and a similar mating flange on the bottom of the valve actuator. Thus, when the valve actuator is placed upon the valve, the mounting flanges face and flatly abut against each other. Thereafter, bolts extend through registering apertures in the mounting flanges and threadably engage nuts to thereby secure the mounting flanges together.
One disadvantage of this previously known means for securing the valve actuator to the valve mounting flange is that the mounting flange on the valve actuator is relatively expensive to construct and significantly adds to the overall cost of the valve actuator.
A still further disadvantage of the previously known means for securing the valve actuator to the valve is that significant bolt and nut clearances must be provided both between the flange and the valve actuator and the flange and the valve body. Due to these required bolt and nut clearances, the combined valve and valve actuator are overly and unnecessarily bulky in construction. This increased bulk in construction presents a particularly serious problem where compactness of the valve and valve actuator is either desired or required.
A still further disadvantage of the previously known means for fastening the valve actuator to the valve is that the actual attachment of the valve actuator to the valve is time consuming in practice and, accordingly, involves high labor costs. Furthermore, it is often desirable to use the same valve actuator on a plurality of different valves so that the valve actuator must be repeatedly attached to and detached from the respective valves. Such attachment and detachment of the valve actuators to and from the valves is time consuming in practice.